在前面一些学习中,原本把闭包给理解成了block虽然有非常多类似之处,但block还是有他自己的独特之外。近日,在写oc/swift混合编码时,有时候须要swift回调oc,oc回调swift 。
因此我把swift中的 block 常见的声明和写法作一个总结。
以免兴许忘了。好查阅。废话不说多,上样例:
// // blockDemo.swift // swiftDemo // // Created by apple on 14-6-29. // Copyright (c) 2014年 fengsh. All rights reserved. // import Foundation //无參无返回值 typealias funcBlock = () -> () //或者 () -> Void //返回值是String typealias funcBlockA = (Int,Int) -> String //返回值是一个函数指针,入參为String typealias funcBlockB = (Int,Int) -> (String)->() //返回值是一个函数指针,入參为String 返回值也是String typealias funcBlockC = (Int,Int) -> (String)->String class blockDemo { //block作为属性变量 var blockProperty : (Int,Int) -> String = {a,b in return ""/**/} // 带初始化方式 var blockPropertyNoReturn : (String) -> () = {param in } var blockPropertyA : funcBlockA? //这写法就能够初始时为nil了,由于生命周当中,(理想状态)可能为nil所以用?var blockPropertyB : funcBlockB! //这写法也能够初始时为nil了,由于生命周当中。(理想状态)觉得不可能为nil,所以用! init() { println("blockPropertyA = (blockPropertyA) , blockPropertyB = (blockPropertyB)") println("blockProperty = (blockProperty) , blockPropertyNoReturn = (blockPropertyNoReturn)") } func testProperty(tag:Int) { switch (tag) { case 1: self.blockPropertyNoReturn("OK GOOD") case 2: if let exsistBlock = self.blockPropertyA { let result = self.blockPropertyA!(7,8) println("result = (result)") } case 3: if let exsistBlock = self.blockPropertyB { let fc = self.blockPropertyB(1,2) fc("输出") } default: let ret = self.blockProperty(3,4) println(ret) } } //block作为函数參数 func testBlock(blockfunc:funcBlock!)//使用!号不须要再解包 { if let exsistblock = blockfunc { blockfunc() //无參无返回 } } func testBlockA(blockfunc:funcBlockA!) { if let exsistblock = blockfunc { let retstr = blockfunc(5,6) println(retstr) } } func testBlockB(blockfunc:funcBlockB!) { if let exsistblock = blockfunc { let retfunc = blockfunc(5,6) retfunc("结果是") } } func testBlockC(blockfunc:funcBlockC!) { if let exsistblock = blockfunc { let retfunc = blockfunc(5,6) let str = retfunc("终于果结是") println(str) } } }
运行測试码:
var bk = blockDemo() //block设置前,啥也没有输出 bk.testProperty(0) bk.testProperty(1) bk.testProperty(2) bk.testProperty(3) println("==============设置block属性================") bk.blockProperty = { (a :Int,b:Int) -> String in let c = a*100+b return "(a)*100+(b) = (c)" } bk.testProperty(0) bk.blockPropertyNoReturn = { (param:String) -> () in println("input param value is : (param)") } bk.testProperty(1) bk.blockPropertyA = { (a:Int,b:Int) -> String in let c = a*100+b*200 return "(a)*100+(b)*200 = (c)" } bk.testProperty(2) bk.blockPropertyB = { (a:Int,b:Int) -> (String)->() in func sumprint(result:String) { let c = a + b; println("sumprint func print:parame :(result) (a) + (b) = (c)") } return sumprint } bk.testProperty(3) println("==============属性block完毕================") println("==============函数block为nil时无输出================") bk.testBlock(nil) bk.testBlockA(nil) bk.testBlockB(nil) bk.testBlockC(nil) println("==============函数block操作================") bk.testBlock({ //do something println("无參无返回值block 运行") }) bk.testBlockA({ (a:Int,b:Int) -> String in let c = a*400+b*1000 return "(a)*400 + (b)*1000 is (c)" }) bk.testBlockB({ (a:Int,b:Int) -> (String)->() in func sumprint(result:String) { let c = a / b; println("sumprint func print:parame :(result) (a) / (b) = (c)") } return sumprint }) bk.testBlockC({ (a:Int,b:Int) -> (String)->String in func sumrsult(res:String) -> String { let c = a*a+b*a return "(res) (a)*(a)+(b)*(a) = (c)" } return sumrsult })以上包含了block声明和使用
以下是输出结果
blockPropertyA = nil , blockPropertyB = nil blockProperty = (Function) , blockPropertyNoReturn = (Function) ==============设置block属性================ 3*100+4 = 304 input param value is : OK GOOD result = 7*100+8*200 = 2300 sumprint func print:parame :输出 1 + 2 = 3 ==============属性block完毕================ ==============函数block为nil时无输出================ ==============函数block操作================ 无參无返回值block 运行 5*400 + 6*1000 is 8000 sumprint func print:parame :结果是 5 / 6 = 0 终于果结是 5*5+6*5 = 55
好了。我想这个比文字语方描写叙述的更为清楚吧。
如有不明确或其他奇怪写法,欢迎踢馆。。
。。。